There is nothing worse to see than a beautiful natural stone paving patio which has turned green. Natural stone paving turning green can be quite a common occurance, especially in North facing gardens. Because natural stone is permeable it can act like a magnet to algae growth which, as long as the conditions are right (damp, permeable surface) will happily breed.
Fear not however. If you do have a north facing garden and still love the idea of installing a natural stone paving patio, then there a few measures you can take to reduce and minimize algae growth.
1. Choose a hard natural stone paving
What makes certain types of natural stone hard is that they are physically dense. While all natural stone paving is permeable harder stones are much less porous. Therefore they will be much more resistant to algae growth and to staining in general. Some of the hard stones we recommend for north facing gardens are Kandla Grey, Raj Green, Buff & Silver Buff.
2. Use an impregnating paving sealant
Another way to reduce algae growth is to use an impregnating paving sealant. This will seal the surface of the natural stone paving and prevent the algae growth from establishing itself. There are a few common misconceptions about using paving sealant. One of the most common ones is that sealing natural stone paving will make the surface of the stone glossy. This can be the case when using cheap paving seals. However we always recommend using the market leader in seal products, Lithofin. Lithofin supply a product called stain stop. While stain stop will make the stone appear ever so slightly darker it will not leave a sheen or gloss. Always take professional advice before sealing natural stone paving.
3. Removing algae from natural stone paving
While algae does look ugly it wont cause any long term damage to your natural stone paving patio and is also easy to shift so if you do have an algae problem with your garden paving there is no reason to panic. One way to shift algae is to treat affected areas with bleach. Simply dilute bleach with water and apply to affected areas. Leave the bleach to work ts magic for a few moments before washing it away with clean water. It might be necessary to treat stubborn areas a few times but persevere and you will shift the troublesome green stuff. There is also a product available from lithofin called outdoor cleaner which works in the same way as bleach.
The overall conclusion is that even if you have got a wet, north facing garden, with a bit of thought you can use natural stone paving for your garden paving and still have a beautiful algae free patio. If you need any advice on natural stone in north facing gardens we are open 7 days a week and advice is freely given
Steve Walley London Stone